Research on the pressure relief mechanism and application of roof dense drilling of gob side entry retaining by roadway-side filling

In gob-side entry retaining (GER) by roadway-side filling, the long cantilever beam structure formed by the goaf roof subjects the filling wall to significant compressive stress under its self-weight and overburden load, often resulting in severe deformations such as floor heave. The S1212 working face of the Ningtiaota Coal Mine was utilized as the engineering background for this study. Through field monitoring of deformations and support component loads, the study revealed the deformation and failure mechanisms of the surrounding rock. This analysis led to the proposal of a novel, optimized control technology centered on roof-dense drilling. In order to validate the efficacy of the proposed methodology, a numerical model was established to replicate field conditions. Various dense drilling parameter schemes were comprehensively evaluated through systematic simulation. The validity of the model was confirmed through the analysis of field monitoring data. The quantitative evaluation metrics were established, including the surrounding rock control rate and support force reduction rate. Subsequent analysis examined the impact of dense drilling angle and height on surrounding rock deformation. Additionally, the study elucidated the control mechanism of roof dense drilling technology in weakening the long cantilever beam and improving the surrounding rock stress environment. Preliminary field tests demonstrated that, in comparison with engineering practices that did not incorporate roof dense drilling, the implementation of this technology led to a substantial enhancement in the control of surrounding rock deformation. This enhancement was characterized by an increase in the control rate by 50.56%, as well as a reduction in the support force required on the filling wall by 60.45%. This approach effectively optimized the surrounding rock stress environment, achieving effective control of roadway stability. Consequently, this research provides a theoretical foundation and practical methodology for stability control in GER roadways under analogous mining conditions.